1. Field of the Invention
The present invention relates fan motor controllers and more particularly, to a small-sized fan motor controller, which eliminates the use of a Hall sensor and is inexpensive to manufacture.
2. Description of the Related Art
Conventional fan motor controllers commonly have the following drawbacks:
1. A Hall sensor is used to detect the polarity address of the rotor of the fan motor for speed control. The use of the Hall sensor greatly increases the cost of the fan motor controller. Further, the installation of the Hall sensor is complicated.
2. The high potential field effect power transistor for driving the fan motor is not in full conduction during working. Therefore, the high potential field effect power transistor wastes much power supply, and the temperature of the high potential field effect power transistor is high during its working.